As this picture show:
The blue line is what I want. However, I can't find anything about it on the Internet. All I know is that create a class inherited TreeControl, by doing so, it become dragable.
As this picture show:
The blue line is what I want. However, I can't find anything about it on the Internet. All I know is that create a class inherited TreeControl, by doing so, it become dragable.
You are looking for an owner-drawn control.
Here is one example: https://www.codeproject.com/Articles/19900/CRHTree-An-Owner-drawn-CTreeCtrl-that-has-Open-Clo
Yours going to be more complicated, as you would need to know that some of the items are not only source
and destination
of those arrows, but also may be a pass-through. Are you planning to adjust how far right the line is drawn based on the text of all visible items in between? And change it when user expands / collapses them?